<p>100Cr6 bearing steel poses significant challenges during the laser powder bed fusion (LPBF) process. The coarse martensite plates and semi-coherent interface precipitates in its microstructure severely limit its tribological properties. An innovative atmosphere engineering strategy is proposed by this study. By precisely controlling the N₂ content in the protective atmosphere during printing (0, 1, 3, and 5%), the microstructure of 100Cr6 formed via LPBF was systematically optimized, thereby improving its wear resistance. The study found that when the N₂ content was 3%, a high-density dislocation network formed within the material, and the martensite plates were significantly refined. More importantly, the precipitated phase transformed from Cr₇C₃-type carbides to Cr₂N-type nitrides, and the interface with the matrix changed from semi-coherent to coherent interfaces. With improvements in microstructure, the hardness of 100Cr6 increased from 621.2 HV in an Ar atmosphere to 661.9 HV in a 3% N₂ atmosphere. Concurrently, the average coefficient of friction decreased from 0.78 to 0.56, and the wear rate decreased from 0.16 × 10⁻⁶ mm³/(N·m) to 0.07 × 10⁻⁶ mm³/(N·m). This study provides new insights into the additive manufacturing of high-performance bearing steels through atmosphere control.</p> Graphical Abstract <p></p>